An electronic device such as portable terminal, mobile terminal, and smart phone mostly provides functions such as phone call, voice recording, and video recording. To support the phone call, voice recording, and video recording functions, the electronic device requisitely includes a microphone for converting a sound to an electric signal.
The electronic device such as smart phone includes a plurality of microphones including a microphone for the phone call and a microphone for the video recording.
When a user wants to input a particular one of multiple sound sources through the electronic device and a location of the microphone of the electronic device has directivity toward the voice signal input, it can overcome ambient noise input.
When software processing is applied to cancel the noise of the voice input through the microphone array, beam can be formed in a particular direction from the microphone array. As such, the beamforming technique is used to form the beam using the microphone array and to exhibit the directivity in the desired direction from the microphone.
When the directivity is obtained in the user's voice direction using the beamforming technique, an energy corresponding to the voice signal from directions outside the beam can be attenuated and the voice signal input from the desired direction can be selectively acquired. By virtue of the beamforming technique, the microphone array can suppress part of an indoor ambient noise such as computer fan noise and TV sound, and reverberations reflected from an object such as furniture and wall. For example, the microphone array can obtain a higher Signal to Noise Ratio (SNR) from the voice signals of the desired beam using the beamforming technique. Hence, the beamforming can play an important role in spatial filtering which points the bema to the sound source and suppresses every signal input from the other directions.
However, the conventional beamforming technique applies a linear filter, which can enhance or attenuate the signal of the known sound direction, to the input signal, and is widely used in a system using the microphone array. Disadvantageously, its performance is affected by the location and the direction of the voice signal.